IRC LOADINGSA DEERENDRA PRASAD

Loads, Forces and Stresses to be considered in the design

1. Dead Load2. Live Load3. Impact of Live load4. Water currents5. Longitudinal forces: a. Tractive or Braking force b. frictional resistance to bearings6. Centrifugal forces7. Buoyancy

8. Earth pressure incl. Live load surcharge

9. Temperature effects10. Deformation effects11. Secondary effects12. Wind loads13. Wave pressures14. Impact due to floating

bodies15. Erection effects16. Seismic forces

DEAD LOAD

DEAD LOAD CONSISTS OF LOADS OF ALL COMPONENTS OF SUPER STRUCTURE:

DECK SLAB AND GIRDERS

FOOT PATHS

WEARING COAT

KERB

HAND RAILING

LIVE LOAD

ALL BRIDGES SHALL BE DESIGNED AS PER THE

FOLLOWING INDIAN ROAD CONGRESS LOADINGS:

IRC CLASS A

IRC 70 R LOADING

IMPACTImpact allowance is a percentage of the applied live load and is for the

dynamic action of live load as listed in table.

Type of bridge

Class A and Class B loading

Class AA and 70 R loading

For spans 3.0 to 45 m

For Spans than

less 9.0m

For Spans or

9.0 m more

Tracked vehicle

Wheeled vehicle

Tracked vehicle

Wheeled vehicle

RCC concrete bridges

4.5/ (6+span length)

25% upto 5m reducing linearly to 10% for 9m

25% 10% upto 40m and as per chart for above 40m

25% upto 12m and as per chart for above 12m

Steel bridges

9/ (13.5+ span length)

10% for all spans

25% upto 23m and as per chart for above 23m

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WIND LOAD

WIND PRESSURE & VELOCITY (Cl. 212.3 of IRC: 6-2000)

H V P H P V H P V

0 80 40 15 128 107 60 168 183

2 91 52 20 136 119 70 173 193

4 100 63 25 142 130 80 177 202

6 107 73 30 147 141 90 180 210

8 113 82 40 155 157 100 183 217

10 118 91 50 162 171 110 186 224

Where H = Ave. height in m of the exposed surface above Ground level/ bed level/ water level V = horizontal velocity of wind at height H in Km/ hr P = horizontal wind pressure at height H in Kg/ m2

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